We're hearing a song that was popular in South Africa in the 1980s, popular even though it was banned. The song was called "Asimbonanga," which means "We Have Not Seen Him." He was Nelson Mandela, who by then had been in prison for more than two decades. This morning we reached the writer of that song, Johnny Clegg, in South Africa.

JOHNNY CLEGG: I am part of the generation that grew up never knowing Nelson Mandela. We were not allowed to see his likeness or mention him or carry a photograph. That would get you four years in jail.

MONTAGNE: Johnny Clegg is white. For many years he performed in a racially mixed band, though that was illegal under South African apartheid laws. He says the song came to him one morning when he awoke to the sound of gunshots - one of the signs of social unrest.

CLEGG: I began writing this song. It started off really as a song about my feeling very down and hopeless. And then while I was writing I thought, well, who can actually cross these dirty waters? Who's person who can bridge you and me, every South African? And when it came down to it, it was Mandela. So I used his name. I thought this is what we really are looking for.

(SOUNDBITE OF SONG, "ASIMBONANGA")

CLEGG: (singing) We are all islands till comes the day we cross the burning water.

MONTAGNE: With his reference to islands, Johnny Clegg was playing off a famous line by the poet John Donne: No man is an island.

CLEGG: And I thought Mandela is on Robben Island and as long as he is on the island, we are all islands here on the mainland. And in order to basically set ourselves free, we have to free him.

STEVE INSKEEP, HOST:

The song became an anthem for many of Mandela's supporters, and years later Mandela came out on stage to dance with Johnny Clegg.

(SOUNDBITE OF ARCHIVED RECORDING)

NELSON MANDELA: Where there enters music and dancing, that makes me at peace with the world.

CLEGG: He was somebody who made you feel that what you were saying was important and he always waited for you to finish speaking and he asked very interesting questions. He didn't ask questions where you felt that he was just trying to engage in conversation. He would try and extract some information about whatever topic you were discussing.

MONTAGNE: The memories of Johnny Clegg, who wrote the song "We Have Not Seen Him," about Nelson Mandela, and finally did see him walk free.